The low-latency deterministic network (LLDN) protocol defined in the IEEE 802.15.4e amendment is intended for factory automation applications that require very low latency and large networks, such as automotive manufacturing. However, LLDN does not provide priority support to properly deal with real-time traffic or dynamic channel configuration capabilities to cope with unreliable channels. Moreover, it offers a limited scalability, as the cycle time grows linearly with the number of network nodes. This paper proposes the priority-aware multi-channel adaptive (PriMulA) framework, which introduces in the LLDN priority-aware scheduling, multichannel communication, adaptive channel selection, and channel blacklisting. PriMulA supports a higher number of network nodes than the LLDN protocol while keeping short cycle times. In addition, PriMuLA avoids deadline miss and improves the network reliability. It maintains the interoperability with LLDN standard nodes and can be implemented on commercial off-the-shelf devices. This paper presents the framework, a schedulability analysis, comparative simulations, and a proof-of-concept implementation.